Existing data sources for heart failure research offer advantages and disadvantages for CER. Clinical registries collect detailed information about disease presentation, treatment, and outcomes on a large number of patients and provide the "real-world" population that is the hallmark of CER. Data are not collected longitudinally, however, and follow-up is often limited. ⋯ Linking clinical registries with other databases to assess longitudinal outcomes holds great promise. The Federal Coordinating Council for Comparative Effectiveness Research recommends further efforts on longitudinal linking of administrative or EHR-based databases, patient registries, private sector databases (particularly those with commercially insured populations that are not covered under federal and state databases), and other relevant data sources containing pharmacy, laboratory, adverse events, and mortality information. Advancing the infrastructure to provide robust, scientific data resources for patient-centered CER must remain a priority.